Adjustable helmets made up of a front shell, a back shell and fastening means are well known in the field of sports equipment, and especially in the field of hockey helmets. Many of the older adjustable helmets that have a front and back shell use fastening means such as screws and bolts to hold the front and back shells together. One disadvantage of fastening means such as screws and bolts is that the wearer is forced to disassemble the two sections of the helmet in order to make the necessary adjustments to the helmet size. Often, this means that a wearer will have to make more than one adjustment to get the proper helmet size, since the adjustments cannot be made with the helmet on the wearer's head. A further disadvantage of this type of assembly is that the wearer must have the proper tools on hand, such as a screwdriver, in order to make the necessary adjustments. Often the correct tools are not readily available in situations where they are needed, namely in hockey rinks.
One attempt at an improved fastening device is demonstrated in U.S. Pat. No. 5,956,776 issued to Bauer Inc. U.S. Pat. No. 5,956,776 describes an adjustable helmet with a front shell, a back shell and a cam shaped locking device that is movable between either one of a locking position and an adjustment position. The overlapping portions of the front shell and the back shell both have engaging members that consist of parallely extending teeth. In the locked position, the two sections of extending teeth engage each other in order to prevent longitudinal displacement of the shells relative to one another. While the adjustable helmet of U.S. Pat. No. 5,956,776 enables the user to adjust the helmet while it is positioned on the wearer's head, without the need for additional tools, the parallely extending teeth create significant friction between the two shells during adjustment. This friction between the engaging teeth makes it difficult for the wearer to easily slide the two shells into a new selected position.
Clearly, there exists the need in the industry for an adjustable helmet that can not only be adjusted while positioned on a wearer's head, without additional tools, but also for a helmet having a front and back shells that can be moved easily relative to one another for accurate size adjustment.